Write blockers are devices that allow acquisition of information on a drive without creating the possibility of accidentally damaging the drive contents. They do this by allowing read commands to pass but by blocking write commands, hence their name.
There are two ways to build a write-blocker: the blocker can allow all commands to pass from the computer to the drive except for those that are on a particular list. Alternatively, the blocker can specifically block the write commands and let everything else through.
There are both hardware and software write blockers.
Commercial Hardware Write Blockers
Hardware write blockers can be either IDE-to-IDE or Firewire/USB-to-IDE. Simson prefers the IDE-to-IDE because they deal better with errors on the drive and make it easier to access special information that is only accessible over the IDE interface. You may feel differently.
- ICS Drive Lock $195
- Wiebetech write-blockers for 2.5"/3.5" IDE, SCSI, SATA, ...